Widespread allegations that powerful Crown Prince Mohammed bin Salman (also known as MBS) played a role in journalist Jamal Khashoggi's murder has thrown American plans in the Middle East into disarray, analysts say.

Martin Indyk, a top Middle East policymaker under Bill Clinton, said President Donald Trump had in effect tried to subcontract policy in the region to Saudi Arabia and Israel as he lessens US commitments.

But Indyk said bin Salman instead brought headaches for Washington - not only Khashoggi's killing but in Yemen where the United States is backing a Saudi-led bombing campaign against Houthi rebels.

"Mohammed bin Salman needs Trump - his very survival depends on Trump working with him," said Indyk, now at the Council on Foreign Relations.

"So we have the opportunity - if we decide we're not going to ask the [Saudi] king to remove him discreetly - to ... sit down with him and say, 'listen, we can't go on like this'," Indyk said.

"But I don't think Trump has any concept of the need to do that, let alone how to do that, and therefore I fear that Mohammed bin Salman will survive, but he will continue on the path that only advantages Iran and gets the United States continuously into trouble."

In an interview with the Wall Street Journal, Trump was asked about bin Salman's possible involvement in Khashoggi's murder. "He's running things and so if anybody were going to be, it would be him," the president responded.

Despite the evidence and international pressure, the crown prince has denied any role in the killing of Khashoggi, a critic of bin Salman who wrote for The Washington Post.

'Permanently weakened'

The United States has pushed ahead with a bid to create a new security and political alliance with six Gulf Arab states, Egypt and Jordan in part to counter Iran's expansion in the region.

Saudi officials raised the idea of a security pact in advance of Trump's visit last year to Saudi Arabia, where he announced a massive arms deal.

Joseph Bahout, a scholar at the Carnegie Endowment for International Peace, said the crown prince will need to show he is tough at home but will now face "constant blackmail" from abroad.

"It will play out, paradoxically, in very divergent directions. If MBS survives this crisis and he stays in power and becomes king, he will be a permanently weakened monarch, but very fierce at the same time," Bahout said.

Bin Salman may attempt to show he is a solid US ally by taking an even harder line against Iran, enemy number one for the Trump administration, or, in a less likely scenario, by enacting liberal reforms, Bahout said.

But the heir apparent could also need to please Turkey, which has been leaking details about Khashoggi's murder.

Turkey ties

Bahout said President Recep Tayyip Erdogan could pressure Saudi Arabia to repair ties with Turkish ally Qatar, which is under a blockade from Gulf Arab states, or to ease pressure on the Muslim Brotherhood, which the kingdom has seen as a threat for its role in Arab Spring protests.

"So he [MBS] will be subject to a whole range of demands and extortions in ways that could contradict one another. And he will be in a difficult position," Bahout said.

Gary Grappo, a former US ambassador to Oman and deputy chief of mission in Riyadh, said bin Salman had solidified power to a level where he is unlikely to be removed - but that Western powers would be increasingly wary of him after Khashoggi's death.

"The taint of this will be very hard to scrub from the hands of Mohammed bin Salman - most definitely in the short to medium term and perhaps, let's see, in the long term," said Grappo, a distinguished fellow at the University of Denver.

After decades of Saudi Arabia buying US weapons and enjoying Washington's protection, Grappo doubted Saudi Arabia could easily switch to another supplier such as Russia or China.

"I think the balance is much more in our favour, which gives the president far more leverage to deal with this matter than he has let on," Grappo said.